What do you think: Are those exercises on dimished 7th chords usefull ? As for example, Philipp´s exercises for the independence of the fingers are exclusively build over those chords. Dohnanyi uses them also in his set of exercises (i think exercises 9-11). The hand is sometimes extensively stretched while playing them. Adele Marcus and Rosina Lhevinne also favoured them. What do you think ?